Currently, updates to a pull request are marked in one big text area 'description' without structure. The resulting description, which is a combination of the manually entered description and 0 or more auto-generated update blocks, is not very readable.
Moreover, when v3 is created, there should only be a reference to v2. The reference to v1 is no longer necessary. Since currently this is free-text being appended, the reference remains.
It would be better if the status updates are handled in a separate field, so that the description is only used by the author himself. This will also allow for a more structured update and avoid references to older revisions but the previous one.